This invention relates to a novel polyester, especially a polyester having various side chains, as well as to a process of producing the same, especially to that of using a monoepoxy compound as one comonomer component.
In order to modify polyesters for the purpose of improving the fluidity, interfacial adhesiveness or interfacial transferability of polyesters or of improving the compatibility or surface-treating property thereof, it is generally well known to vary the kinds of diols, dicarboxylic acids or derivatives thereof, which are components of constituting polyesters, as well as the constitutive proportions thereof or to introduce various comonomer components into polyesters thereby to attain the intended objects. However, modification of resins by such method results in variation of the structure or sequence of the main chain of the resulting resin. Therefore, the intended modification of resins would often have harmful effects on the resulting resins, for example, the mechanical strength of the resins themselves would be lowered by such modification. On the other hand, where an interfacial transferability is imparted to resins, a sufficient effect could not be obtained in most cases. Where resins are modified in order that various properties such as interfacial transferability, moisture-absorbability, hydrophilicity, water-repelling property or non-adhesiveness are imparted to resins themselves or the compatibility with solvents or other resins is controlled, or where resins are used as an adhesive between substances of different kinds, introduction of pertinent side chains into the resins would be rather better than variation of the structure of the main chain of the resins in order to attain the object with ease.
It is an object of this invention to provide a novel polyester, especially that which has been modified to have various side chains as mentioned above and which is useful.
It is another object of this invention to provide a process for producing such a novel polyester in which a monoepoxy compound and a dicarboxylic acid are used as comonomer components. In the polyester to be prepared by the process of this invention, the substituents on the monoepoxy compound used are in the side chains of the polyester molecule but not in the main chain of the polyester. Therefore, by selecting proper monoepoxy compounds, the intended modification of polyesters can be effected and accordingly, the adhesiveness and compatibility of the polyesters with other resins may thereby be improved.